Synthesis and Characterization of Volatile, Fluorine-Free β-Ketoiminate Lanthanide MOCVD Precursors and Their Implementation in Low-Temperature Growth of Epitaxial CeO₂ Buffer Layers for Superconducting Electronics

Abstract

A new class of volatile, low-melting, fluorine-free lanthanide metal-organic chemical vapor deposition (MOCVD) precursors has been developed. The neutral, monomeric Ce, Nd, Gd, and Er complexes are coordinatively saturated by a versatile, multidentate ether-functionalized beta-ketoiminato ligand series, the melting point and volatility characteristics of which can be tuned by altering the alkyl substituents on the keto, imino, and ether sites of the ligand. Direct comparison with conventional lanthanide beta-diketonate complexes reveals that the present precursor class is a superior choice for lanthanide oxide MOCVD. Epitaxial CeO(2) buffer layer films can be grown on (001) YSZ substrates by MOCVD at significantly lower temperatures (450-650 degrees C) than previously possible by using one of the newly developed cerium beta-ketoiminate precursors. Films deposited at 540 degrees C have good out-of-plane (Deltaomega = 0.85 degrees ) and in-plane (Deltaphi = 1.65 degrees ) alignment and smooth surfaces (rms roughness approximately 4.3 A). The film growth rate decreases and the films tend to be smoother as the deposition temperature is increased. High-quality yttrium barium copper oxide (YBCO) films grown on these CeO(2) buffer layers by pulsed organometallic molecular beam epitaxy exhibit very good electrical transport properties (T(c) = 86.5 K, J(c) = 1.08 x 10(6) A/cm(2) at 77.4 K).

Synthesis and characterization of new alkaline earth metal β-ketoiminates. The first structurally characterized strontium β-ketoiminate

“…The use of ketoiminates of group 2 is limited to barium [4] and magnesium [5] derivatives, although a wide range of bketoimines can easily be prepared from b-diketones and various amines [6]. Functional b-ketoimines with either O-or N-donor arms were shown to be able to provide additional donor sites for controlling the nuclearity, and thus the volatility of Ba [4], Ce [7] or Mg [5] species. Monomeric, volatile barium precursors were thus obtained by using appended polyether ÔlariatsÕ NCH 2 CH 2 (OCH 2 CH 2 ) x OR (x = 0-2, R = Me, Et) [4].…”

Organic Electro‐Optic Modulators with Substantially Enhanced Performance Based on Transparent Electrodes

“…There are various growth methods for TC materials, including metalorganic chemical vapor deposition (MOCVD), ion-assisted deposition (IAD), pulsed laser deposition (PLD) and sputtering [13][14][15][16][17][18][19][20][21][22]. Table 15.2 shows a few of the TCs of interest, such …”

Hafnium(IV) chloride complexes with chelating β-ketiminate ligands: Synthesis, spectroscopic characterization and volatility study

“…deposition (MOCVD) for the growth of thin films. This is because of their easy accessibility of ligands synthesis, inexpensive, ready availability of the starting material, and controllable of steric and electronic effects [1][2][3][4][5][6][7][8].…”